In installations for the production of cement clinker from raw meal, which is preheated and calcined before the burning operation, it is often necessary to divide a stream of hot cement raw meal into two meal discharges, that is, to convey hot raw meal into one and/or another meal discharge. Thus, for example, in the installation for the production of cement clinker from cement raw meal as shown in European patent document EP-B 0222 044 published Mar. 8, 1989, the preheated raw meal exiting downward from the next-to-last (second-lowest) cyclone stage must be divided in a controlled way into a calcination zone lying in the clinker-cooler off-gas line (tertiary air line), on the one hand, and a calcination zone lying in the rotary-kiln off-gas line, on the other. What is more, in certain dual-train installations (twin installations) where the cement raw meal of one train, precalcined in the rotary-kiln off-gas line, undergoes final calcination in the calcination zone of the other train, operated on hot clinker-cooler off-gas, after the installation has been started up, precalcined cement raw meal exiting from the lowest cyclone stage of the rotary-kiln off-gas train must be admitted by means of a changeover flap not to the rotary kiln but to the secondary calcination zone of the other train, which is ready for operation.
The distribution or changeover of the stream of hot raw meal has heretofore been effected with a distributor housing, to the top of which the hot meal delivery line can be connected and to the bottom of which two hot meal discharges can be connected, so that the distributor housing is also called a "breeches pipe" because of its shape. In the breeches pipe, a flap is pivotably arranged, by means of the pivot actuation of which flap the stream of hot cement raw meal, which can exhibit a temperature of, for example, 800 to 900.degree. C., is distributed or changed over. The pivotable flap in particular is obviously subjected to severe thermochemical and abrasive wear.
Also subjected to severe wear are "impingement gates," which in cement plants are built transversely into a hot-gas line coming from the rotary kiln and/or from the clinker cooler and have the task of uniformly distributing or suspending, over the hot-gas cross section, preheated cement raw meal, which is introduced into the hot-gas line from the side.
What is more, in cyclone suspension-type preheater trains having cyclones arranged one above another through which hot gas flows in order to heat cement raw meal, "flap boxes" or "oscillating feeders" and also double oscillating feeders are built into the meal downpipes, in which boxes one or two weighted oscillating flaps are integrated, which have the task of holding back the stream of hot gas on the one hand, and on the other hand, by means of pivoting of the flaps, of allowing the stream of hot raw meal to pass downward through the meal downpipe after a certain solids burden. These oscillating flaps are also subjected to severe wear.